To shield against electromagnetic waves, simple metallic coatings of copper or aluminum are predominantly used, the wave being nearly completely reflected and its energy not being dissipated. When non-magnetic metals are used for reflecting an electromagnetic wave, there is merely a minimal loss of energy; hardly any dissipation occurs.
In the context of ferro- or ferrimagnetic resonance, magnetic films, such as FeNi foils, effect a partial absorption of the electromagnetic energy, partially converting it into other forms of energy, in particular thermal energy, thereby attenuating the wave. In this case, however, the frequency range of the energy dissipation is limited and essentially covers the low MHz and kHz range. The shielding against an electromagnetic wave can be improved as a function of the magnetic permeability; the so-called skin effect prevents the wave from penetrating more deeply into a housing. However, the inherent disadvantage is that the range of maximum energy absorption is not adjustable.
H. Okumura, D. J. Twisselmann, R. D. McMichael, M. Q. Huang, Y. N. Hsu, D. E. Laughlin and M. E. McHenry, Magnetic and Structural Characterization and Ferromagnetic Resonance Study of Thin Film HITPERM Soft Magnetic Materials for Data Storage Applications, J. Appl. Phys. 93, 2003, pp. 6528-30, describes a device made of one or of a plurality of layers of thin films of amorphous magnetic materials, each film having a resonance frequency.
In Microwave Permeability of Ferromagnetic Thin Films With Stripe Domain Structure, J. Appl. Phys. 81, 1997, pp. 4057-59, O. Acher, C. Boscher, B. Brulé, G. Perrin, N. Vukadinovic, G. Suran and H. Joisten describe a planar, amorphous ferromagnetic film having stripe domains.
G. Perrin, J. C. Peuzin, and O. Acher, in Control of the Resonance Frequency of Soft Ferromagnetic Amorphous Thin Films by Strip Patterning, J. Appl. Phys. 81, 1997, pp. 5166-68, and M. Vroubel, Y. Zhuang, B. Rejaei and J. Burghartz, in Patterned FeNi Thin Film for RF and Microwave Components, J. Magnetism and Magn. Materials 258-259, 2003, pp. 167-169, discuss applying thin, parallel strips of amorphous, ferromagnetic films to a substrate using photolithography. This allows the frequency of the ferromagnetic resonance of a film to be shifted to higher values.